Method and apparatus for controlling refrigeration

ABSTRACT

A thermal sensor ( 20 ) located in the centre of a food simulant composition ( 24 ) linked to a remote measuring indicating and/or regulating device ( 28 ). The temperature of the food simulant changes in the same way as food stored in its vicinity and is unaffected by the movement of the ambient air which varies in temperature dramatically. This allows an actual reading and recording of stored food temperature and the regulation of the temperature within a refrigerated space by a thermostat ( 16 ). Its uses are mainly for frozen, chilled and refrigerated food, and the reading of temperature of food cooked for example in micro-wave ovens.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for controllingrefrigeration apparatus. An example of the application of the inventionis to a method and apparatus for controlling the operation of domesticand commercial food storage refrigeration apparatus including deepfreeze apparatus. However, the invention also provides, as such, theapparatus which operates in accordance with the aforesaid method forcontrolling such refrigeration apparatus, and provides temperaturesensing apparatus.

Further aspects of the invention relate to the use of the method andapparatus for the control of apparatus for raising the temperature offood and the like, for example microwave cooking apparatus. Furtheraspects of the invention relate to a method and apparatus for conductingthermal tests and calibration in relation to refrigeration and heatingapparatus.

There is disclosed in WO 94/10546 (reference P51957WO) a method andapparatus applicable to temperature sensing in relation to refrigerationequipment in which provision is made for a means to enable visualinspection, of temperature sensing apparatus (for example a conventionalbulb and meniscus column-type thermometer) which has been stored in arefrigerator and then removed for inspection, without the attendantinaccuracy of temperature measurement arising from immediate response ofthe thermometer to the raised air temperature outside the refrigeratoror, if such inspection is effected without removal from therefrigerator, the effect of the ingress of external warm air into therefrigerator.

For this purpose, the apparatus of the WO 546 specification provides forthe thermometer to be entirely encased within a transparent capsulecontaining ethylene glycol.

In this way the WO 546 apparatus seeks to offset the effect of suddenchanges of air temperature on temperature sensing apparatus used inrelation to refrigeration equipment.

In a similar way, the disclosure in DE 30 32 684 A1 provides for the useof a thermal barrier material to surround the temperature sensor in arefrigerator in order that the effect of opening the door of therefrigerator will be cushioned.

In the references cited against the WO 546 specification there arerelated disclosures concerning the use of thermal inertia and barriersystems for similar or related reasons.

We have discovered that the technical approach adopted in these priorproposals to the sensing of temperatures in refrigeration apparatus andto the control of such apparatus, is technically subject to significantshortcomings in terms of seeking to alleviate the symptoms of themallaise (inaccurate temperature sensing) without looking to see what isthe actual technical step needed for the purpose in terms of the realfunction of the temperature sensing system.

SUMMARY OF THE INVENTION

In accordance with the principles of our discovery, the proper basis forevaluating the only temperature of interest within a refrigerator(namely the temperature of the food therein enclosed) is to, in essence,sample the food temperature therein. Now, while invasive foodtemperature sampling by use of inserted probes and the like is fraughtwith practical difficulties and liberally fenced-around with foodhygiene regulations, (so that actual food internal temperature sensingbecomes a practical impossibility), we have discovered that there is apractical alternative approach which is not foreshadowed in the priorart, and in accordance with this principle the proper approach to thesensing of such temperatures is by internal sensing within a simulatedbody of food. Thus, in accordance with this approach, the method andapparatus of the invention provides the means whereby temperature caneffectively be sensed from within food stored within the refrigerator,or in the case of a heating system (such as a microwave oven) fromwithin food being heated in such a heating appliance.

By adopting an approach in which, instead of seeking to damp out theeffect of incoming warm air and providing instead the means to sensetemperature from within the food itself, yet without the hygiene andrelated problems of invasive probes, there is provided a method andapparatus which has the capability of providing the user with that whichhe or she actually wants namely the temperature of the food in question.

This latter factor is of great relevance, we have discovered, sincealthough (as the prior art teaches) the air temperature within arefrigerator or deep freeze rises rapidly when the door is opened, theactual effect of the air temperature on the stored food is often quitemarginal and there can be a temperature difference between the air andthe stored food of 10° C. or more while an unmodified air temperaturesensing system in a refrigerator (as is conventionally provided indomestic appliances) will react relatively wildly to such fluctuations,and such is obviously undesirable for energy conservation reasons.Equally there is the converse situation where the approach has beentaken that such over-reaction of the temperature control system isineffective and wasteful, but it is equally true that mere damping ofthe system is not the effective answer either because damping merelylowers the amplitude of the reactive peaks of the system withoutaddressing the underlying problem or question.

The method and apparatus of the embodiments of the present inventiondoes address that underlying question and provides the means foraddressing it in a repeatable and scientifically based manner whichavoids the hygiene implications of invasive probes yet addresses thequestion to be answered directly without merely seeking to amelioratethe technical consequences of the problems which arise in practice withexisting apparatus.

Thus in the embodiments of the present invention the temperature sensoris located within a body of food simulant and at a distance from thesurface thereof which corresponds to an average stored food articlesize, with the result that the sensed temperature corresponds closely tothat of an article of food located alongside the food-simulant articlewithin the refrigerator.

Of course, in the case of a food article placed in the refrigerator arelatively short time previously, there will be the potential fortemperature inaccuracy, but such temperature divergences are inherent inany temperature changing system of the refrigeration or heating kind,and the question to be addressed is how does the system respond (afternewly-added articles have temperature-adjusted) to fluctuations causedby door-opening or automatic defrosting or the like?

An important aspect of the embodiments of the present invention concernsthe nature of the food simulant material itself, and in the principalembodiments described below the food simulant simulates food by being amaterial adapted for repetitive use over a significant period (wherebyrepetitious unacceptable servicing replacement in a regularly useddomestic article of this kind is avoided), but which is capable ofsimultaneously responding thermally in the manner of a foodstuff bybeing such a material itself. Thus, the embodiments of the presentinvention as described below provide an exact simulation of the thermalproperties of a foodstuff by providing for the selective use of a such amaterial itself to model the thermal characteristics required to besensed. In this manner the embodiments enable the apparatus and methodto provide a signal which can be used either for controllingrefrigeration apparatus or for indicating food temperature, or indeedboth, so as accurately to reflect the thermal behaviour of an item offoodstuff place alongside the temperature-sensing and food-simulatingarticle. Actual examples of the materials to be employed are describedbelow. These materials are usually in gel or wax-like format and thusrequire suitable encasement for practical handling in the refrigerationand/or heating appliance environment. Accordingly, the food simulantmaterial is provided with a casing which typically may comprise aplastic moulding corresponding in size to a typical food article forrefrigerational storage in the envisaged use environment, and which mayadditionally be provided with one or more further layers of material tosimulate the thermal effects of packaging which is conventionallyemployed in relation to articles stored in refrigerators or deepfreezers. This latter aspect of the thermal characteristics of thesimulated article of food may be incorporated into the overall thermalpackage without the need for providing specific physical counterparts ofthe packaging as such. For example, the effect of such packaging mightbe reasonably closely approximated to by adopting a somewhat larger sizefor the overall simulated food article. However, such an approach is notstrictly in accordance with the principles of some of the embodiments ofthe present invention, for which the approach is to adopt, fortemperature sensing purposes, a simulated food article of a sizecorresponding to a typical stored food article and having within it notonly simulated food with the temperature sensing device therein, butalso simulated packaging to correspond with the conventional packaging,but not of course overlooking the requirement for durability in terms ofthe intended use of the device within the refrigeration or otherapparatus over a period of years.

In relation to the temperature sensing devices used in the embodimentsof the invention themselves, conventional hardware may be employed andsuch will usually be in the form of electrically-responsive thermosensormeans as employed in known refrigeration apparatus. From such athermosensor, the output emf may be fed to the control port or inputgate of the refrigeration apparatus control system and/or thecorresponding connection of a digital or analogue thermal readout.

Thus, using presently available technology, there will usually be arequirement for a hard-wired connection to the thermal sensing devicewithin the food-simulating article and for this purpose suitableconvenient and durable means may be provided. For example, in the casewhere the method and apparatus is employed for the control of thetemperature of a refrigerator or deep freeze various approaches may beadopted to the positioning of the sensing article. In one approach thearticle may be a single article and chosen for placement within therefrigeration cabinet at a suitable location corresponding reasonablyclosely with that of the food article which will be most likely toaffected by the thermal change (such as door opening) with which thesystem is intended to cope. Alternatively, a series of food-simulatingarticles may be provided within the thermal cabinet for placementamongst the food articles and with suitable hard-wiring connections, forexample disconnectable plug-in connectors, though such is not deemed tobe commercially attractive practical option for conventional domesticuse, despite the fact that the hard wiring transmits voltages only ofthe order of millivolts. Alternative technical solutions to the signaltransmission question may be evolved including wireless transmission orother transmission systems not requiring the physical use of hard wiringloose connectors. One option might be to provide a series offood-simulating articles plugged into the cabinet of the apparatus atsuitable locations and from which the signals would be monitored andevaluated on an overall assessment basis.

Another aspect of the invention relates to the use of thefood-simulating article and the contained thermal sensor therein inrelation to a method for controlling the operation of refrigeration ordeep freeze apparatus so as to achieve significant energy savings inrelation to power consumption for driving the pump of conventionalrefrigeration apparatus. In accordance with this aspect of the inventionthe control method and apparatus are adapted to provide a degree ofcontrol of the refrigerant pump (or other driveable thermal transferapparatus) such that the extent of operation of the pump matches to aclose approximation that which is actually required to produce thedesired level of refrigeration of the food, avoiding the peaks andtroughs associated with conventional control systems which sense airtemperature only and the corresponding thermally damped peaks andtroughs of the prior art apparatus discussed above. Thus, theseembodiments of the invention provide improved refrigeration unitresponse pattern (in terms of pump drive periods and/or formal heattransfer quantum per unit time). This result is achieved by providing inaccordance with the principles of the invention a refrigerant drivesystem control signal which is generated on the basis of afood-originating temperature-dependent control signal. This has theresult that the power consumption of the refrigerant system matches theactual requirements of the apparatus and its enclosing cabinet insteadof being related to relatively irrelevant factors such as the airtemperature in the cabinet and/or a perceived requirement to damp theresponsiveness of the control system. In this manner there are achievedsignificant energy savings which tests have indicated will frequentlyamount to as much as 33% of overall consumption.

Accordingly, the embodiments of this aspect of the invention providemethod and apparatus whereby energy conservation is achieved by drivingthe heat-transfer refrigeration apparatus in accordance with controlsignals derived from a sensor system providing control based uponsignals effectively emanating from the very food within the temperaturecontrol cabinet which is to be temperature controlled, such signalsbeing based upon a food simulant, which may indeed be a foodstuffitself, approximating in physical characteristics (including size andheat transfer properties) to an average or typical foodstuff to bestored. In this way there is provided a system in which the powerconsumption characteristics are based upon a model closely approximatingto that which heat transfer theory would devise to conform with theobjective of minimisation of fuel consumption for actual foodrefrigeration purposes.

Likewise a further aspect of the invention provides a method andapparatus adapted to enable calibration of a temperature control system,for example in existing refrigeration apparatus, so as to enable suchapparatus to be calibrated to provide a refrigeration effect adapted(with energy-effective control) to achieve specific internal foodtemperatures.

A still further aspect of the invention provides a method and apparatusapplying the above principles in relation to inward heat transfer tofood or the like articles as opposed to the above outward hest transferie to cooking or heating as opposed to refrigeration.

(Here follows the priority application)

Food Simulant Temperature Measuring Device

This invention is a thermometric device to shadow the temperature offood stored within its vicinity by sensing the temperature of a foodsimulant which is itself a food product encapsulated in a recipient,without being affected by the changes of the ambient temperature. Theinvention is a generic product covering different applications involvingstorage of food and other commodities which must be kept within aspecific temperature range.

The invention relates to the method and apparatus applicable 1) to theremote sensing of a food simulant to indicate the temperature of foodstored in cold rooms, refrigerated or heated containers and otherstorage spaces for reading, recordal or other purposes, 2) to regulatethrough the medium of a thermostat of the temperature of cold rooms,refrigerated or heated containers or other storage areas, 3) to indicatethe temperature of food cooked in ovens particularly micro wave ovens.

The invention will ensure that the products stored or cooked are at orwithin the degrees of temperature suggested or imposed by HealthAuthorities or other regulated bodies.

Application for Cold Temperature

1) We shall first describe the application for all foods and perishablesstored at low temperatures which require a refrigerated element forprocessing, storage, manufacture transport and the like.

2) The invention is for use in any refrigeration system which suffersthermal shocks in refrigerators, freezers, cold stores, production linecooling and/or freezing, land, sea or air transport and any otherrefrigerated containers generally offering storage facilities toovercome temperature fluctuations experienced when monitoring airtemperature.

3) The problem of obtaining correct food temperature in refrigeratedcontainers occurs because of the frequent and closely spaced sequencesof door openings, restocking of food, hot gas or electric defrost,auto-defrost, cleaning and any other causes giving rise to suddenchanges in air temperature and consequently of the erratic movement oftraditional thermometers—digital or tubular, placed therein. Howeverfood temperature will vary only gradually either downwards or upwardsover a period of time without being affected by the erratic fluctuationof the air temperature. Consequently monitoring the temperature of theair cannot give any indication of the temperature of the food;comparative readings of air and food temperature in the same containershow that they can vary considerably, often by well over 10° C.

4) Misunderstanding the temperature may lead to the finding ofunacceptable food standards under existing food hygiene regulationsleading to penalties or eventual destruction of the food. It is a wellestablished fact that bacteria becomes active when temperatures exceed5° C. and multiply rapidly above 8° C. and it is therefore reprehensibleto store food to be consumed without ensuring that it has been stored atall times at the right temperature. A probe thermometer will give anaccurate reading of food temperature but can cause cross contaminationwhich is a serious health hazard; devastating consequences of crosscontamination were in evidence in the John Barr butchers E-coli case(heard in a U. K. Court).

5) The present invention consists of an inner recipient which containsfood simulant that has the consistency of average food; this innerrecipient consequently represents an average food. In its centre is atemperature sensor device. This inner recipient is enclosed in an outerperforated hard plastic case designed to give an accurate temperaturereading of food within an average commercial packaging. The sensor beinglocated at the centre of the device being 16 to 18 mm from its closestsurface becomes in effect a thermal probe within its own food. Thisallows accurate temperature monitoring of food located in the vicinityof the invention, or of the refrigeration running controls as laterdescribed. The invention indicates at all times the temperature at 16 mmto 18 mm inside the food simulant and as a corollary within the foodstored in its vicinity without damaging said food or risking the realpossibility of cross contamination.

6) The invention can be fitted with audible or visual warnings forexample when the temperature of the food simulant exceeds its safetylimit. The warning could be located either inside a refrigerator or onthe outside. Such a device from a temperature recording devicestimulated by air would be to all intents and purposes ineffectualbecause of the constant fluctuations of the air temperature which wouldtrigger each time the warning alarm and cause confusion and irritationto people within hearing distance.

7) A prior proposal in this technical field is to be found in GR 2286884originating from the present applicant which discloses a system in whicha bulb or stem type thermometer is mounted within a transparentcontainer and immersed in a transparent liquid or gel having relativelyhigh terminal inertia so that the indicated temperature provided by thethermometer can be accurately read after the thermometer has beenremoved from the refrigerator for inspection; the thermal inertia of theliquid or gel surrounding the thermometer serves to maintain theindicated temperature of that thermometer for at least the length oftime reasonably required to read and record that temperature.

8) However, this prior proposal does not always meet the needs ofcommercial establishments where a system for constant monitoring of thetemperature within a refrigerated enclosure is needed, together with, ifrequired, a digital monitoring and recordal system, or printed recordingor otherwise, of the indicated temperature. A visual inspection systemcannot effectively meet such requirements and a different approach isthus required.

9) By providing a device in which temperature determination is effectedby means of a remote-sensing thermal probe with associatedmonitoring/recordal facilities a system is offered whereby theadvantages of our prior system mentioned above in terms of temperaturedetermination of actual food as opposed to air temperatures is obtainedfor commercial or other purposes with many added advantages, and like inthe prior system gives the temperature within the food without touchingthe food itself.

10). The electronic sensor can be connected by electric wire to anexternal embodiment either permanently or temporarily depending onrequirements to check the temperature of the food simulant and thus thefood stored in its vicinity, the sensor inserted in the recipient can beconnected which will be plugged in as and when the user requires to viewthe food temperature.

11) The user may need to check the temperature of refrigerated or frozenfoods stored in different zones within a refrigerated space to establishtemperature variants so that vulnerable products can be stored in morefavourable positions for example in a multi-deck self service displayrefrigerated cabinet where the difference in temperature from base totop can vary quite considerably; inside an average size refrigeratedcontainer the difference in temperature can often be 8° C. if not more.The small size of the recipients of the invention will enable the userto place them in different zones of the refrigerated space in order tomonitor their temperature; as explained in paragraph 10 this can be doneat regular intervals or with a permanent connection.

12) where multiple refrigeration systems are in operation, devices ofthis kind may be provided in as many locations as required, with thethermal output data routed in a monitoring system permitting monitoringand recordal of temperature data for each location on a time-relatedbasis, whereby a visual display, digital recordal or print out can beobtained indicating temperature levels of food or other refrigeratedproduct in the said locations over a given period of time, regardless ofair movement. General temperature fluctuations particularly where thereare perishable goods can also be monitored and recorded and any abnormalmovements in any particular area immediately signalled.

13) In transportation of goods loaded in refrigerated transportcontainer, their temperature cannot usually be monitored accuratelywhich may lead to disputes between shippers and buyers. The inventionwill supply the necessary data and confirm the movement of temperatureduring the voyage including period of transit. Temperature determinationis effected by the invention linked to a data transmission conduit suchas a conductor or the like transmission device linked to a digitalrecordal facility. For road transport this can be linked to a warningdevice as mentioned in 6 above to alert the driver of any unusualtemperature fluctuations of the goods.

14) The invention is an ideal and effective method of teaching foodmonitoring control. It clearly demonstrates the variation between airand food temperature and highlights the difference in temperature ofdifferent zones in the refrigerated space thus providing irrefutableproof of the correct food temperature.

15) The invention offers the advantages of great flexibility andconsistency in its application. It can be connected to a sophisticatedcomputerised system to which various facilities such as recordal,statistical, breakdown warning systems can be added when required. Itoffers a low cost method to monitor the true temperature of food storedin several zones of a refrigerated space: by placing a device on thetop, middle and lower shelves, each connected to a remote digitalread-out, a clear picture is obtained at all times of the efficiency ofthe refrigeration equipment.

16) Because of the accuracy provided by the right application of theinvention another of its benefits is to signal the possibility of theonset of refrigeration failure; if regular monitoring over a period oftime of the temperature of the food taken in similar condition ofrefrigeration shows a slow but continuous rise in temperature, it islikely that a fault is developing in the refrigeration system whichshould be looked into as soon as possible. The warning could save lossof refrigerated products and possibly reduce the damage to theequipment.

17) An embodiment of the invention detailed in paragraph 5) above willnow be described by way of example with reference to the accompanyingdrawings in which FIG. 1 shows an outer container 3 representing theskin, surface or wrapping of food encapsulating an inner container 4filled with a composition 5 simulating food, in which is inserted thesensor 6 linked to a read-out 1 indicating the temperature of saidsubstance by a connecting cable 2. The sensor is inserted at about 17 mmwithin the inner container.

Application for Hot Temperature

18) Food Hygiene Regulations in the EC stipulate that hot food must bekept at a certain minimum temperature. It is usually 63° C. or higher.In some areas like Scotland food that is re-heated must reach 82° C.Probes are usually the only temperature measuring device available.

19) The present invention offers a device which monitors the temperatureof the hot food either as a permanent fixture or temporary to be used asand when required. For this application the materials required aredifferent from the ones used in the previous chapter requiring coldtemperature but otherwise the principle remains the same.

Application for Thermostat

20) The thermostat regulates the temperature inside the refrigeratedspace. When the temperature exceed a pre-set level it activates therefrigeration cycle; the mechanism is switched on automatically by theincrease of air temperature usually at the air-in. As explained airtemperature varies constantly with door openings and other activitiesassociated with refrigeration storage already mentioned which result infrequent power surges as the refrigeration equipment switches on and offcausing excessive wear and tear on the system's components, totallyunnecessary as the stored food actually retains a stable temperature.

21) The invention uses the principle of food simulation to control thethermostat by encapsulating the sensor in the inner recipient fitted ata distance of 17 mm to its surface to equate the refrigeration to foodtemperature. With the invention, it is the temperature of the foodsimulant shadowing the temperature of the food itself stored in itsvicinity which activates the refrigeration cycle and therefore ensurethat the cooling system functions when is it actually required.

22) When the thermostat is controlled by a food simulant the thermostatchanges its operation; tests show that over a period of 6 hours, athermostat activated by “air sensors” will start the refrigeration cyclean average of 18 times, whereas if activated by food sensors as per ourinvention the average is reduced to 7 times bringing an appreciablesaving in power of about 20 percent and saving on maintenance and wearand tear of the system. It is a fact that the refrigeration andair-conditioning industry is a growing world-wide industry and is anenormous consumer of electricity 20% savings, or indeed any saving willbring large benefits to the environment.

Application for Temperatures Tests in Micro-Wave Ovens

23) Cooking in micro-wave ovens is uncertain due to several factors suchas ageing of the micro-wave guide cover or defrosting of food stored atan unknown temperature. Cooking time is calculated to cook unfrozenfood, and the defrosting facility is usually based on the recommendedfreezing temperature of −18 degC/0 degF consequently when food is frozenat a lower temperature, the defrost facility will cease to operatebefore the food is completely defrosted. The cooling period willtherefore start with food still partly frozen which will beinsufficiently cooked at the end of the cooking period. The error iscaused because it is usually assumed chat freezers maintain the food atthe right temperature and that the thermostat read-out is a thermometerreadout; the temperature of the food itself is not checked with areliable food thermometer and the result is a health hazard.

24) In a microwave oven, food is cooked from within and the airtemperature is not affected. Consequently the only method to check thefood temperature is to use a probe. We have already pointed out the highrisks of using probes in food for consumption.

25) The invention consists of a pack of food simulant for food of aparticular weight, density and composition, supplied with a temperaturesensor to read the temperature of the pack before and after being cookedand comparative tables if required. The object is to test the efficiencyof the micro-wave oven.

26) Initially in a chilled state; the invention is designed to be cookedin the micro-wave oven to reach a specific temperature over a set periodof time. When the time is over, the temperature of the pack is takenwith the sensor. If the temperature of the pack reaches the saidspecific temperature, the oven cooks satisfactorily. If it does not, thecooking time must be adjusted on the comparative charts supplied withthe invention which will then be used to indicate the period of cookingfor particular types of food.

27) The pack is taken in a frozen state after being stored in aparticular freezer. The procedure as in 26 is repeated. The temperatureof the invention is recorded and the pack is then cooked and itstemperature again recorded and the cooking time adjusted accordingly. Afurther check may be advisable based on the new calculation to make surethat the temperature is now correct and eventually rectified and thecharts corrected accordingly for future cooking. Since it is not unusualto find that freezers maintain a temperature which is not therecommended one, it is strongly suggested that each freezer is testedwith the invention before using the food stored therein and that each isused with its own charts.

28) The invention can be used to effectively calibrate micro-wave ovensby checking its efficiency with the tables supplied with each pack.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of examplewith reference to the accompanying drawings in which FIG. 1 shows adiagrammatic representation of apparatus for controlling article heattransfer apparatus in accordance with the invention;

FIGS. 2A, 2B and 3 show plan, perspective and sectional views through anembodiment of temperature sensing apparatus employing a thermal sensorwithin a body of food simulant material;

FIG. 4 shows a further embodiment of the thermal sensor of FIGS. 2 and3;

and FIGS. 5 and 6 show graphic representations of the operation of priorart apparatus (FIG. 5) and apparatus according to an invention (FIG. 6)illustrating the reduced number of operating cycles within a givenperiod produced by the apparatus of the invention.

DETAILED DESCRIPTION

As shown in FIG. 1 apparatus 10 for controlling article heat transferapparatus 12 connectable to an energy source 14 comprises controlapparatus 16 to control the operation of the heat transfer apparatus 12in accordance with sensed thermal characteristics.

A chamber 18 is provided to contain one or more of the articles (notshown) to or from which heat transfer is to be effected, duringoperation of the heat transfer apparatus.

Chamber 18 is in operative association with the heat transfer apparatus12 so that the latter can cause heat transfer to or from the chamber andhence to or from articles contained therein.

Control apparatus 16 comprises a thermal sensor 20 responsive to sensedthermal characteristics within the chamber.

Control apparatus 16 further comprises a thermal sink or body 22associated with sensor 20 and having a thermal capacity to modify theresponsiveness of control apparatus 16 to thermal characteristics withinchamber 18.

In accordance with the invention, thermal sink or body 22 comprises atemperature sensing food article 24 which is provided within chamber 18and comprises a body of food-simulant material 26 having thermal sensor20 located therein and adapted to provide a food-originatingtemperature-dependent control signal to control apparatus 16 and thus toheat transfer apparatus 12 based upon the temperature within the foodsimulant material 26 at a defined distance from the surface of foodarticle 24 so as to control the heat transfer apparatus 12 in accordancewith a thermal model based on actual required food temperatures.

In this embodiment, energy source 14 is a conventional electrical supplysource and such is connected to heat transfer apparatus in the form ofthe usual refrigeration heat pump operated by control apparatus 16 inthe usual way but under the control of thermal sensor 20 in accordancewith the principles of the present invention.

Heat transfer apparatus 12 may be provided in the form of refrigerationapparatus or in the form of cooking apparatus for example microwaveheating apparatus.

Turning to the nature of food simulant material 26, this may be providedin this embodiment either as a food grade liquid or as a food grade waxsuch as cheese wax. In the case of a food grade liquid, a suitableexample is obtainable from the firm Ellis & Everard in the UK under thetrade mark Pricerine 9091, which is a glycerine food grade vegetable oilin the form of an odourless syrupy liquid. It is also known as glycerolfood grade vegetable oil.

In the case of the wax material, this may be in the form of cheese waxobtainable in the UK from the British Wax Refining Co Limited ofRedhill. For example, cheese wax 2110 grade for dipping/coating cheeses.The wax is a blend comprising a mixture of hydrocarbon waxes and foodgrade white oil.

Other food grade material may be suitable for the purpose on the basisof the characteristics discussed above and apparent from the twoexamples disclosed above.

Turning now to the embodiments shown in FIGS. 2, 3 and 4, these show thethermal sensor 20 of FIG. 1 used instead in association with a digitalreadout 28. Sensor 20 is located within the body of food-simulantmaterial 26 which is contained by a cylindrical capsule 30 positionedwithin a rectangular body 32 of simulated packaging material. A bracket34 mounts readout 28 on the packaging 32 and is capsule 30 and serves asa conduit for hardwiring conductors not shown.

In the embodiment of FIG. 4, there is additionally provided a clip ormounting 36 for screwing or adhering to the refrigeration cabinet.

Capsule 30 and simulated packaging 32 and (34) and clip or mounting 36may all comprise suitable plastics materials moulded or otherwise.

The diagrams of FIGS. 5 and 6 illustrate the mode of operation of theapparatus of FIG, FIG. 6 showing that over a six hour period suchapparatus made only 10 starts in terms of commencing operation of theheat transfer apparatus whereas the corresponding conventional equipmentshown in FIG. 5 made 30 such starts during a similar period illustratingthe significant reduction in use and wear and tear on and energyconsumption by the refrigeration apparatus.

The plots of FIGS. 5 and 6 are of temperature against time as sensedfrom a thermal probe located in condenser equipment of the heat transferapparatus.

1. A method of controlling article heat transfer apparatus comprisingthe steps of: a) providing drivable heat transfer apparatus connectableto an energy source; b) providing control apparatus for said heattransfer apparatus to control operation thereof in accordance withsensed thermal characteristics; c) providing a chamber to contain atleast one article during operation of said heat transfer apparatus; d)providing said chamber in operative association with said heat transferapparatus and causing the latter to effect heat transfer to or from saidchamber; e) providing said control apparatus comprising a thermal sensorresponsive to sensed thermal characteristics within said chamber; f)providing said control apparatus further comprising one of a thermalsink and a body associated with said thermal sensor and having a thermalcapacity to modify a responsiveness of said control apparatus to thermalcharacteristics within said chamber; and g) said one of said thermalsink and body comprising a temperature-sensing food simulating articleprovided within said chamber and comprising a body of solidfood-simulant material able to retain its shape without the support ofan external container and having said thermal sensor located therein indirect contact with the food simulant material, the food simulantmaterial simulating the thermal properties of a foodstuff and adapted toprovide a food-simulating temperature-dependent control signal to saidheat transfer apparatus based upon the temperature within saidfood-simulant material at a defined distance from a surface of said foodsimulating article so as to control said heat transfer apparatus inaccordance with a thermal model based on actual required internal foodtemperature.
 2. A method according to claim 1 further comprising thestep of providing said heat transfer apparatus comprising refrigerationapparatus.
 3. A method according to claim 1 further comprising the stepof providing said heat transfer apparatus comprising cooking apparatus.4. A method according to claim 1, further comprising the steps of:providing monitoring apparatus for said heat transfer apparatus tomonitor operation thereof in accordance with sensed thermalcharacteristics; providing said monitoring apparatus comprising afurther thermal sensor responsive to sensed thermal characteristicswithin said chamber; providing said monitoring apparatus comprising oneof a thermal sink and body associated with said further thermal sensorand having a body of solid food simulant material able to retain itsshape without the support of an external container and having saidthermal sensor located therein in direct contact with the food simulantmaterial, the food simulant material simulating the thermal propertiesof a foodstuff and adapted to provide a food simulating temperaturedependent monitoring signal so as to monitor the heat transfer apparatusin accordance with a thermal model based on actual required internalfood temperatures.
 5. A method according to claim 4, further comprisingthe step of: providing said monitoring apparatus comprising means fortransmission of the monitoring signal to a monitoring/recordal facility;and the monitoring/recordal facility recording the monitoring signal. 6.Article heat transfer apparatus according to claim 4, wherein saidmonitoring apparatus comprises means for transmission of the monitoringsignal to a monitoring/recordal facility.
 7. For use in the methodaccording to claim 1, a temperature-sensing food simulating articlecomprising a body of food-simulant having a thermal sensor one of: a)located therein, and b) adapted for location therein.
 8. Article heattransfer apparatus comprising: a) drivable heat transfer apparatusconnectable to an energy source; b) control apparatus for said heattransfer apparatus to control operation thereof in accordance withsensed thermal characteristics; c) a chamber to contain at least onearticle during operation of said heat transfer apparatus; d) saidchamber being in operative association with said heat transfer apparatusand adapted to cause the latter to effect heat transfer to or from saidchamber; e) said control apparatus comprising a thermal sensorresponsive to sensed thermal characteristics within said chamber; f)said control apparatus further comprising one of a thermal sink and abody associated with said thermal sensor and having a thermal capacityadapted to modify a responsiveness of said control apparatus to thermalcharacteristics of said chamber; and g) said one of said thermal sinkand body comprising a temperature-sensing food simulating articleprovided within said chamber and comprising a body of solidfood-simulant material able to retain its shape without the support ofan external container and having said thermal sensor located therein indirect contact with the food simulant material, the food simulantmaterial simulating the thermal properties of a foodstuff and adapted toprovide a food-simulating temperature-dependent control signal to saidheat transfer apparatus based upon the temperature within saidfood-simulant material at a defined distance from a surface of said foodsimulating article so as to control said heat transfer apparatus inaccordance with a thermal model based on actual required internal foodtemperature.
 9. Apparatus according to claim 8 wherein said heattransfer apparatus comprises refrigeration apparatus.
 10. Apparatusaccording to claim 8 wherein said heat transfer apparatus comprisescooking apparatus.
 11. Article heat transfer apparatus according toclaim 8, further comprising: monitoring apparatus for said heat transferapparatus to monitor operation thereof in accordance with sensed thermalcharacteristics; said monitoring apparatus comprising a further thermalsensor responsive to sensed thermal characteristics within said chamber;said monitoring apparatus further comprising one of a thermal sink andbody associated with said further thermal sensor and having a body offood simulant material having said thermal sensor located therein indirect contact with the food simulant material, the food simulantmaterial simulating the thermal properties of a foodstuff and adapted toprovide a food simulating temperature dependent monitoring signal. 12.An apparatus for monitoring a heat transfer apparatus comprising: a) athermal sensor responsive to sensed thermal characteristics within achamber; b) one of a thermal sink and a body associated with saidthermal sensor and comprising a body of solid food simulant materialable to retain its shape without the support of an external containerand having said thermal sensor located therein in direct contact withthe food simulant material, the food simulant material simulating thethermal properties of a foodstuff and adapted to provide a foodsimulating temperature dependent monitoring signal; c) the monitoringapparatus comprising means for transmission of the monitoring signal toa monitoring/recordal facility so as to monitor the heat transferapparatus in accordance with a thermal model based on actual requiredinternal food temperatures.
 13. An apparatus for monitoring according toclaim 12, wherein the monitoring/recordal facility includes acomputerized system.
 14. A method of monitoring article heat transferapparatus comprising the steps of: a) providing drivable heat transferapparatus connectable to an energy source; b) providing monitoringapparatus for said heat transfer apparatus to monitor operation thereofin accordance with sensed thermal characteristics; c) providing achamber to contain at least one article during operation of said heattransfer apparatus; d) providing said chamber in operative associationwith said heat transfer apparatus and causing the latter to effect heattransfer to or from said chamber; e) providing said monitoring apparatuscomprising a thermal sensor responsive to sensed thermal characteristicswithin said chamber; f) providing the monitoring apparatus comprising athermal sensor responsive to sensed thermal characteristics within achamber, the monitoring apparatus comprising means for transmission ofthe monitoring signal to a monitoring/recordal facility means fortransmission of the monitoring signal to a monitoring/recordal facility;g) said one of said thermal sink and body comprising a temperaturesensing food simulating article provided within said chamber andcomprising a body of solid food simulant material able to retain itsshape without the support of an external container and having saidthermal sensor located therein in direct contact with the food simulantmaterial, the food simulant material simulating the thermal propertiesof a foodstuff and adapted to provide a food simulating temperaturedependent monitoring signal, so as to monitor the heat transferapparatus in accordance with a thermal model based on actual requiredinternal food temperatures.
 15. An apparatus for monitoring according toclaim 14, wherein the monitoring/recordal facility includes acomputerized system.